Took me a while to understand the difference between thermostat and thermometer, it's alright. Unfortunately I wouldn't trust information from a local pet store, they usually have no idea what they're talking about. (I saw a ball python at PetCo and the humidity was far too low, and the hide was WAY too big. I told an employee about it and she insisted it was fine.) Fake plants are crazy expensive and you can keep the ones you have just as long as you get some that offer a lot of coverage. Do keep us updated.
Edit: Make sure the fake plants you choose aren't tangled, don't have any "loops" and don't have any wires sticking out! I've heard of lots of stories where a snake gets stuck or hurt due to a fake plant. Just some precautions to take.